GB/T 2942-1991 Determination of adhesion strength between vulcanized rubber and textile cords - H extraction method
Some standard content:
Method".
National Standard of the People's Republic of China
Rubber , vulcanized-Determination of static adhesion to textile cord ch-pull testGB/T 2942 --91
Replaces GB2942-82
This standard is equivalent to the international standard ISO4647-1982 "Determination of static adhesion to textile cord for tires - 1 Subject content
This standard specifies the method for determining the static adhesion strength between textile cord and vulcanized rubber for tires. - Pull out
This standard is applicable to cords made of natural fibers, artificial fibers or synthetic fibers. This standard is also applicable to similar cords used in other vulcanized rubber products, but the linear density shall not exceed 800mg/m. 2 Reference standards
GB527 General requirements for physical test methods of vulcanized rubber GB/T2941 Standard temperature, humidity and time for environmental conditioning and testing of rubber specimens GB6038 Rubber test compound preparation, mixing, vulcanization equipment and operation 3 Test principle
Bury the two ends of the cord in the rubber compound according to the specified length, and measure the force required to extract a single cord from the rubber compound along the longitudinal axis. The measured force is the shear force acting on the interface between the cord and the vulcanized rubber. The rubber at both ends and the cord connected in the middle form a specimen shaped like the letter "H". The test method is named after this. 4 Materials
4.1 Specimen: composed of cord and rubber compound.
4.2 Isolation pad: Its function is to facilitate demoulding. It can be made of cotton plain cloth of about 340g/m2 or equivalent material. This material can be original cotton plain cloth or single-sided rubberized cloth. In addition, the rubber compound used to make the sample can be attached to the rubber surface of the cotton fabric by calendering.
4.3 Protective film: In order to prevent the rubber compound from being contaminated, the rubber compound is covered with a polyethylene protective film after being pressed to keep the surface in contact with the cord clean. wwW.bzxz.Net
5 Test load
5.1 Mould
Approved by the State Administration of Technical Supervision on April 25, 1991
Implementation on April 1, 1992
GB/T2942-91
The size of the sample is controlled by the specifications and tolerances of the mould. The sample is prepared by placing a rubber strip with a thickness of Y/2 into two mould cavities with a spacing of Z and a width of C. As shown in Figure 1.
Vulcanized rubber
Put the straightened cord on the rubber strip in a direction perpendicular to the rubber strip, and the spacing between each two cords is L. Then put two rubber strips on the cord, close the mold, put it into the flat vulcanizer, and vulcanize the sample. Usually a mold that can produce multiple identical samples at the same time is used. 5.2 Cord tension device
For a device that provides 0.49±0.01N cord tension, it can be achieved by hanging a 50±1g weight at the end of each cord when preparing the sample. And remove the weight before putting the mold into the flat vulcanizer for vulcanization. The weight can be hook-shaped or clamped on the cord with a clamp. In either case, the total mass of the weight should be 50±1g. 5.3 Testing machine
The testing machine should meet the following conditions:
Must be calibrated and qualified, and the load division value should be less than 1N. a.
Non-inertia tensile testing machines should be preferred. When using inertia tensile testing machines for testing, they should comply with the provisions of 3.3 b.
in GB527 standard.
During the test, the gripper should move at a constant speed of 100±10 mm/min. 5.4 Sample gripper
The shape and size of the gripper are shown in Figure 2. Two upper and lower grippers are required for the test 2]. Instructions for use:
1) Two types of molds can be selected for ISO4647--82. In order to reduce the residual rubber in the mold cord groove, a silicone rubber coated rod strip method is used. It is explained in the appendix. 2] ISO 4647--82 has two types of grippers. Since they may not give the same test results, this standard specifies one type. 171
6 Sample
GB/T 2942- 91
Thread according to the transition fit of the testing machine
6.1 Dimensions
The standard sample should be made of a certain length of cord buried in a rubber strip with a width of 6.4 mm and a thickness of 3.2 mm. Alternatively, the cords may be inserted into the rubber compound with a width of 10 mm and a thickness of 10 mm or a width of 5 mm and a thickness of 3.2 mm. However, the test results obtained from specimens with different embedding lengths are not comparable. 6.2 Preparation
6.2.1 Before preparing the specimen, the mixed rubber should be covered with a protective film to keep the surface of the rubber compound clean. The cords should not be stained with hand sweat, oil, dust, water and other pollutants.
6.2.2 Use scissors or a punch to cut the rubber compound into strips with a width of 6.4 mm and a suitable length, and leave the protective film on the rubber compound. 6.2.3 Cut the isolation liner into strips according to the size of the rubber strip (if the rubber compound has been calendered on the fabric, this step can be omitted) and place it at the bottom of the mold cavity to facilitate demolding.
6.2.4 Place the rubber strip in the mold with the protective film facing up (if the rubber is calendered on the fabric, the fabric side should face the bottom of the mold).
6.2.5 Remove the protective film from the rubber strip and immediately place the cord in a cord candy perpendicular to the rubber strip (note that the part of the cord in the rubber compound cannot directly contact the bare hand). Hang a heavy hammer to make the cord tensile. Remove the protective film from the other part of the rubber strip, and place them on the cord in the mold cavity with the side without the protective film facing down. Cover with an isolation pad and close the mold. 6.2.6 Place the mold in a flat vulcanizer that has been preheated to the vulcanization temperature and remove the tension device from the cord. Adjust the pressure so that the pressure on the mold surface reaches the minimum pressure of 3.5MPa for vulcanization. After vulcanization for the specified time, immediately remove the sample from the mold and cool it at room temperature. 6.2.7 After vulcanization, the sample should not have defects such as lack of glue, bubbles, flattening and damage of the cord. Cut the sample with scissors or a die to make an "H" test specimen. At the same time, be particularly careful to remove all excess glue and do not damage the cord. 172
7 Time interval between vulcanization and testing
GB/T 2942-91
The shortest time interval between vulcanization and testing is 16 hours and no more than four weeks. In order to achieve comparable test results, the tests should be carried out after the same time interval as much as possible. If there are technical requirements, the time interval can be specified separately. 8 Sample conditioning
The conditioning of the sample shall comply with the provisions of GB/T2941. 9 Test temperature and humidity
9.1 The test temperature and humidity shall comply with the provisions of "Standard temperature and humidity of the test room" in GB/T2941. In order to obtain comparable results, any test or a group of tests shall use the same temperature and humidity from beginning to end. 9.2 If a high temperature test is carried out, the sample fixture shall be enclosed in the oven on the testing machine. For any sample, the total heating time in the oven at the test temperature shall not be less than 15 minutes and not more than 60 minutes. Or the specimens are heated in an oven close to the testing machine, then taken out one by one and tested within 15 seconds. The heating temperature and preheating method of the specimens shall be determined as required. 10 Test steps
10.1 Install the two specimen holders on the tensile machine so that the end points of the two holders are 1 mm apart. Position them carefully to ensure that the longitudinal axes of the holders are in a straight line.
10.2 Adjust the moving speed of the tensile testing machine holders to 100±10mm/min. 10.3 Adjust the tensile testing machine force reading so that the indication is zero. Install the specimen in the holder and pass the cord vertically through the gap between the two holders for the test.
10.4 Record the maximum force required to extract the cord from the rubber, accurate to 1N. 11 Test results
11.1 Record the static adhesion of the cord to the vulcanized rubber in Newtons. 11.2 The number of specimens representing the performance of the same sample shall not be less than 8. Take the arithmetic mean, accurate to one decimal place. If the cord breaks before being drawn out during the test, the specimen shall be invalid. Indicate whether there is adhesive attached to the cord.
Test report
The test report shall include the following items:
The name, batch number, specification and origin of the cord. b.
Detailed description of the rubber compound and the curing time and temperature. Test temperature.
Size of the specimen.
Temperature and relative humidity during specimen conditioning. Description of specimens not covered by this standard.
Number of specimens tested.
Test results of all individual specimens and their arithmetic mean. Type of failure.
Test date.
Tester.
A1 Use of silicone rubber-faced spacers
GB/T 2942-91
Appendix A
Preparation of silicone rubber-faced spacers
(reference)
A1.1 There are two methods for preparing the mold for the specimen, as shown in Figure A1. Method B is the commonly used specimen mold. In method A, the cord between the rubber ends of the specimen is clamped between special rods covered with silicone rubber. This method is to clamp the cord between the two ends of the rubber in the middle of the deformable surface instead of in the cord groove when the sample is vulcanized. Therefore, no excess rubber will flow into the gap. This has a certain effect on improving and eliminating excess rubber.
A2 Preparation of silicone rubber compound
A2.1 The compound used should be a self-adhesive silicone rubber with a hardness of about 60IRHD. A2.2 According to the size of the existing mold cover, use two flat templates to press 50-60g of film between two polyester films to make its thickness as uniform as possible to 1.5mm.
It is best to press at a very low pressure in a hydraulic press (should be less than 175kPa). It is more appropriate to use a hand pump press. If necessary, the pressurized plate can be heated to 50-70℃.
A2.3 After pressurizing for 2-3 minutes, check whether the silicone rubber has reached the required thickness. If the thickness of 1.5mm is not reached, 2.0mm is also allowed.
A2.4 Remove the silicone rubber sheet, still protected by polyester film, and place it on a cold flat surface. A3 Preparation of spacers
A3.1 Use a knife, wire brush or similar method to scrape off as much old silicone rubber as possible from the spacers. A3.2 Degrease the spacers in a trifluoroethylene or perchloroethylene vapor bath for 30 to 60 minutes. A3.3 Polish the bonding surface of the spacers with fine gauze. You can also use light sandblasting or steam washing methods, but be careful to prevent unnecessary roughening of the non-bonding surface.
A3.4 Finally, clean the spacers with a cloth soaked in petroleum solvent. After the solvent evaporates, immediately cover it with silicone rubber strips. A4 Bonding procedure
A4.1 Cut the silicone rubber with a polyester protective film into strips according to the bonding surface of the spacers. If the silicone rubber is inevitably thicker, the strip width can be reduced by 1~~2mm (usually the strip width is about 10mm) to prevent excessive overflow. A4.2 Peel off the polyester protective film on one side of the silicone rubber, and place the peeled side on the freshly cleaned bonding surface, and gently press it with your hands to make it fit. Avoid direct contact between your hands and the bonding surface of the silicone rubber and the spacer to prevent contamination from affecting the bonding. A4.3 Prepare two strips at a time. They should be used in pairs, so it is best to mark them with easy-to-identify marks. A4.4 Place the spacers with the rubber side facing up side by side in the appropriate mold. If it is considered appropriate, the polyester film on the top can be removed at this time. To facilitate demolding, another polyester film that is sufficient to cover the mold cavity can be embedded, or the mold release agent polytetrafluoroethylene aerosol can be sprayed on the mold cover. A4.5 After positioning and closing the mold using the matching holes and spacer grooves, put the mold into a flat press. When the flat plate is heated, apply low pressure to spread the silicone rubber. When the temperature reaches 160℃, the positive vulcanization temperature, apply the maximum safe pressure and vulcanize for 15 minutes. A4.6 The spacers are best cooled in the press and in the pressurized mold. If this is not possible, allow the entire mold to cool outside the press. When hot, the silicone rubber is still relatively fragile and susceptible to damage. A4.7 After cooling, carefully remove the coated spacer from the mold. This can be done by removing a stopper that is screwed into the mold so that a thin pry bar can be inserted under the spacer to remove the spacer. 174
GB/T2942—91
A4.8 Excess silicone rubber overflow can be trimmed off or trimmed after oven vulcanization. A4.9 When all re-coated spacers have been plate-cured, condition them at 200℃ for 18 to 24 hours. If trimming has not been done previously, remove the waste edges now.
A5 Number of uses
A5.1 Under normal conditions of use, the spacer is expected to be used for molding specimens at least 500 times before re-coating. Grooves for placing cords
Silicone rubber covered rods
Additional remarks:
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. A-·A Cut
This standard is under the jurisdiction of the Beijing Rubber Industry Research and Design Institute of the Ministry of Chemical Industry. This standard was drafted by Shanghai Dazhonghua Rubber Factory. The main drafter of this standard is Di Can.
This standard is entrusted to the Beijing Rubber Industry Research and Design Institute for interpretation. 1751 Under normal use conditions, the spacer is expected to be used for at least 500 molded specimens before being re-coated. Grooves for placing cords
Silicone rubber coated rods
Additional notes:
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. A-·A Cut
This standard is under the jurisdiction of the Beijing Rubber Industry Research and Design Institute of the Ministry of Chemical Industry. This standard was drafted by Shanghai Greater China Rubber Factory. The main drafter of this standard is Di Can.
This standard is entrusted to the Beijing Rubber Industry Research and Design Institute for interpretation. 1751 Under normal use conditions, the spacer is expected to be used for at least 500 molded specimens before being re-coated. Grooves for placing cords
Silicone rubber coated rods
Additional notes:
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. A-·A Cut
This standard is under the jurisdiction of the Beijing Rubber Industry Research and Design Institute of the Ministry of Chemical Industry. This standard was drafted by Shanghai Greater China Rubber Factory. The main drafter of this standard is Di Can.
This standard is entrusted to the Beijing Rubber Industry Research and Design Institute for interpretation. 175
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